Selective catalytic ethanolysis of C-O bonds in lignite-related model compounds and Xilinguole lignite over difunctional Ni/HZSM-5 in H2-free system

Catalytic cracking of C-O bond is one of the important strategies for conversion of lignite into soluble organic matter. Ni/HZSM-5 was prepared by a modified deposition precipitation method with the Ni mass ratio ranging from 5% to 20% and evaluated by catalytic cracking benzyloxy benzene (BOB) and benzyl ether (BE). BOB was completely converted in ethanol over Ni15%/HZSM-5 under 1 MPa N2 at 240 °C for 2 h, while BE was completely converted at 180 °C. Ethanol could be activated to CH3CH2O· and H· over Ni nanoparticles supported on HZSM-5, which cleaved the C-O bond in BOB and BE. Additionally, the Ni15%/HZSM-5 was also successfully applied in catalytic ethanolysis of resides from ethanolysis Xilinguole lignite (XL) without H2 at 300 °C. The soluble portion yields from ethanolysis of XL and catalytic ethanolysis of residue are 47.8% and 15.1%, respectively. Soluble portion 1 (SP1) and catalytically soluble portion 1 (SP1C) were identified by gas chromatography/mass spectrometry. Different from SP1 mainly containing esters and phenols, SP1C is mainly composed of alkanes, arenes, and esters. In conclusion, catalytic ethanolysis of lignite in H2-free system is a potential way to cleave C-O bonds and prepare lignite-derived organic chemicals.